dirstate-tree: Avoid BTreeMap double-lookup when inserting a dirstate entry
The child nodes of a given node in the tree-shaped dirstate are kept in a
`BTreeMap` where keys are file names as strings. Finding or inserting a value
in the map takes `O(log(n))` string comparisons, which adds up when constructing
the tree.
The `entry` API allows finding a "spot" in the map that may or may not be
occupied and then access that value or insert a new one without doing map
lookup again. However the current API is limited in that calling `entry`
requires an owned key (and so a memory allocation), even if it ends up not
being used in the case where the map already has a value with an equal key.
This is still a win, with 4% better end-to-end time for `hg status` measured
here with hyperfine:
```
Benchmark #1: ../hg2/hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1
Time (mean ± σ): 1.337 s ± 0.018 s [User: 892.9 ms, System: 437.5 ms]
Range (min … max): 1.316 s … 1.373 s 10 runs
Benchmark #2: ./hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1
Time (mean ± σ): 1.291 s ± 0.008 s [User: 853.4 ms, System: 431.1 ms]
Range (min … max): 1.283 s … 1.309 s 10 runs
Summary
'./hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1' ran
1.04 ± 0.02 times faster than '../hg2/hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1'
```
* ./hg is this revision
* ../hg2/hg is its parent
* $REPO is an old snapshot of mozilla-central
Differential Revision: https://phab.mercurial-scm.org/D10550
#require eol-in-paths
https://bz.mercurial-scm.org/352
test issue352
$ hg init foo
$ cd foo
$ A=`printf 'he\rllo'`
$ echo foo > "$A"
$ hg add
adding he\r (no-eol) (esc)
llo
abort: '\n' and '\r' disallowed in filenames: 'he\rllo'
[10]
$ hg ci -A -m m
adding he\r (no-eol) (esc)
llo
abort: '\n' and '\r' disallowed in filenames: 'he\rllo'
[10]
$ rm "$A"
$ echo foo > "hell
> o"
$ hg add
adding hell
o
abort: '\n' and '\r' disallowed in filenames: 'hell\no'
[10]
$ hg ci -A -m m
adding hell
o
abort: '\n' and '\r' disallowed in filenames: 'hell\no'
[10]
$ echo foo > "$A"
$ hg debugwalk -v
* matcher:
<alwaysmatcher>
f he\r (no-eol) (esc)
llo he\r (no-eol) (esc)
llo
f hell
o hell
o
$ echo bla > quickfox
$ hg add quickfox
$ hg ci -m 2
$ A=`printf 'quick\rfox'`
$ hg cp quickfox "$A"
abort: '\n' and '\r' disallowed in filenames: 'quick\rfox'
[10]
$ hg mv quickfox "$A"
abort: '\n' and '\r' disallowed in filenames: 'quick\rfox'
[10]
https://bz.mercurial-scm.org/2036
$ cd ..
test issue2039
$ hg init bar
$ cd bar
$ cat <<EOF >> $HGRCPATH
> [extensions]
> color =
> [color]
> mode = ansi
> EOF
$ A=`printf 'foo\nbar'`
$ B=`printf 'foo\nbar.baz'`
$ touch "$A"
$ touch "$B"
$ hg status --color=always
\x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mfoo\x1b[0m (esc)
\x1b[0;35;1;4mbar\x1b[0m (esc)
\x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mfoo\x1b[0m (esc)
\x1b[0;35;1;4mbar.baz\x1b[0m (esc)
$ cd ..